1. Field of the Invention
The present invention relates to gears used for manufacturing, a printer, a method of using the gears, and the printer manufactured by using the gears.
2. Description of the Related Art
Printers which are capable of printing an image on a sheet on the basis of an input signal are generally known. These printers have a print head, a feeding tray for storing a plurality of sheets, a feeding roller, a conveying roller, a catch tray, and the like. The feeding tray can store a plurality of sheet of various sizes (for example, A4 size, B5 size, legal size, postcard size, and the like). When printing an image on a sheet, the feeding roller contacts with the sheets on the feeding tray 1 and then rotates. Accordingly, one sheet is taken out from the feeding tray. The sheet sent out by the feeding roller is conveyed by the conveying roller. An image is printed on the sheet by the print head while the sheet is conveyed. The sheet printed with the image is discharged to the catch tray by the conveying roller.
The printer comprises a plurality of mechanisms. For example, one mechanism rotates the feeding roller, and other mechanism rotates the conveying roller.
There are many printers that use a single motor to drive a plurality of mechanisms. This type of printer comprises a driving force transmitting device for transmitting driving force to the plurality of the motor. The driving force transmitting device is positioned between the mechanisms and the motor. A driving device is constituted by combining a plurality of gears.
There are cases in which the plurality of mechanisms, which are driven by a single motor, need to be driven independently. For example, sometimes switching needs to be performed between a state in which the conveying roller is rotated without rotating the feeding roller, and a state in which the feeding roller is rotated without rotating the conveying roller.
In order to respond to the above requirements, the driving force transmitting device sometimes comprises a switch gear and a set of driven gears. The switch gear is driven by the motor. Each of the driven gears is engaged with a corresponding mechanism. The switch gear can slide in a direction parallel to the axis of rotation of the switch gear (in other words, the switch gear can move in parallel). The set of driven gears is situated so it has a positional relationship where all of the gears can be engaged with the switch gear.
As the switch gear slides and then stops, it selects a driven gear allows it to be engaged. As the motor rotates in such a state, one selected driven gear rotates, and thereby the one mechanism in engagement with the driven gear is driven. By using the switch gear and the set of driven gears, an arbitrary mechanism can be driven independently from the other mechanisms by a single motor.
For example, FIG. 28A shows a switch gear 200 and a set of driven gears 201 through 204. These gears configure the driving force transmitting device of an inkjet printer for the required set of functions. This inkjet printer has a first feeding tray and a second feeding tray. Moreover, this inkjet printer can execute normal printing and high-speed printing on sheets stored in the first feeding tray. Furthermore, this inkjet printer can perform maintenance on the inkjet head.
The switch gear 200 can slide in a direction shown by an arrow in FIG. 28A. The switch gear 200 is rotated by a driving force from a motor which is not shown. The driven gears 201 through 204 are planed rotatably around a rotation axis 205. The driven gears 201 through 204 can be driven independently. The driven gear 201 is engaged with the first mechanism, which rotates a feeding roller of the first feeding tray (referred to as “first feeding roller” hereinafter) intermittently, so as to send sheets intermittently from the first feeding tray. The driven gear 202 is engaged with the second mechanism, which rotates the first feeding roller continuously, so as to send the sheets continuously from the first feeding tray. The driven gear 203 is engaged with the third mechanism that rotates a feeding roller sending sheets from the second feeding tray (refined to as “second feeding roller” hereinafter). The driven gear 204 is engaged with the fourth mechanism that transmits driving force to a maintenance device.
The switch gear 200 can slide and thereby engage with any of the driven gears 201 through 204. When the driven gear is rotated by the switch gear 200, the mechanism of engagement with the driven gear is activated. The mechanism to be activated is changed by sliding the switch gear 200.
When normal printing is executed on sheets stored in the first feeding tray, the switch gear 200 is slid to a position for engagement with the driven gear 201. Consequently, the driving force from the motor is transmitted to the first feeding roller by the first mechanism. The first mechanism intermittently rotates the first feeding roller so as to send the sheets intermittently. Therefore, the sheets are sent intermittently from the first feeding tray. Specifically, after printing on the first sheet is finished, a subsequent sheet is sent from the first feeding tray. In the normal printing, an image can be printed on a sheet with a high degree of accuracy.
When high-speed printing is executed on sheets stored in the first feeding tray, the switch gear 200 is slid to a position for engagement with the driven gear 202. Consequently, the driving force from the motor is transmitted to the first feeding roller by the second mechanism. The second mechanism continuously rotates the first feeding roller so as to send the sheets continuously. Therefore, the sheets are sent continuously from the first feeding tray. Specifically, once the first sheet is sent from the first feeding tray, a subsequent sheet is sent from the first feeding tray. In the high-speed printing, an image can be printed on a number of sheets in a short amount of time.
The second feeding tray can store sheets that differ in size from the sheets stored in the first feeding tray. For example sheets of A4 size are stored in the first feeding tray, and sheets of B5 size are stored in the second feeding tray. A user can select the size of sheets and print an image on a sheet of the selected size.
When printing on the sheets stored in the second feeding tray, the switch gear 200 is slid to a position for engagement with the driven gear 203. Consequently, the driving force from the motor is transmitted to the second feeding roller by the third mechanism. Accordingly, the second feeding roller is rotated, and thereby a sheet is sent from the second feeding tray.
In the inkjet printer, ink droplets are ejected from the inkjet head, whereby an image is printed on a sheet. Specifically, an actuator (an actuator using a modification of piezoelectric element or electrostrictive element, an actuator that locally heats ink by means of a heater element, or other actuator) of the inkjet head is activated, and the ink droplets are ejected from a nozzle onto a sheet. In the inkjet printer, occasionally bubbles are generated in the ink in the inkjet head, or foreign material is adhered to the nozzle. In such cases, the inkjet head cannot eject ink droplets in the preferred manner. Therefore, the inkjet printer needs to perform maintenance on the inkjet head. When performing maintenance, the bubbles, foreign material and the like are drawn and eliminated from the nozzle of the inkjet head. This operation is generally called the “purge operation”. The purge operation is executed when, for example, the power of the inkjet printer is ON, or at predetermined time intervals. The maintenance device for performing the purge operation has a cap covering a nozzle surface of the inkjet head, and a pump for reducing the pressure inside the cap.
When executing the purge operation, the inkjet head is stopped at a position corresponding to the maintenance device. Then, the nozzle surface of the inkjet head is covered with the cap. At the same time, the switch gear 200 is slid to a position for engagement with the driven gear 204. Consequently, the driving force from the motor is transmitted to the maintenance device by the fourth mechanism. Then, the pump of the maintenance device and the valve for switching the discharge destination of the pump are activated. Accordingly, the pressure inside the cap is reduced. When the pressure inside the cap is reduced, the bubbles, foreign material and the like are drawn out and removed from the nozzle.
As described above, by moving the position of the switch gear 200, the transmission destination of the driving force of the driving force transmitting device is changed.